1.5.1.6 Upgrading MySQL with the Installation Wizard

The MySQL Installation Wizard can perform server upgrades
automatically using the upgrade capabilities of MSI. That means
you do not need to remove a previous installation manually
before installing a new release. The installer automatically
shuts down and removes the previous MySQL service before
installing the new version.

Automatic upgrades are available only when upgrading between
installations that have the same major and minor version
numbers. For example, you can upgrade automatically from MySQL
5.5.5 to MySQL 5.5.6, but not from
MySQL 5.1 to MySQL 5.5.